BIO-TRIBOLOGICAL PROPERTIES AND MICROSTRUCTURE OF SEMICRYSTALLINE AL2O3/PEEK COATINGS ELECTROPHORETICALLY DEPOSITED ON THE TI-13NB-13ZR ALLOY

Tribological applications of titanium alloys in orthopedic surgery and traumatology are limited due to their low resistance to wear and low hardness [1]. Therefore, in order to protect of the alloy surface and improve the performance of titanium alloys in orthopedic implants in friction and wear applications, for example, in the head and acetabulum of endoprostheses, surface treatment is necessary. Electrophoretic deposition (EPD) is a very convenient method for producing the composite ceramic-polymer coatings on metallic substrates. Polyetheretherketone (PEEK) and PEEK-based coatings have often been applied as a sliding material in bio-tribosystems because of their high wear resistance, corrosion resistance and self-lubricating capacity [2-4]. In our previous study, we successfully deposited a well-adhered PEEK coating which improved bio-tribological properties of the Ti-13Nb-13Zr alloy substrate [4]. In the present work, composite Al2O3/PEEK coatings deposited by EPD were applied for further improvement the bio-tribological properties of the Ti-13Nb-13Zr alloy. The deposits exhibited the uniform distribution of powders used for deposition. The PEEK in the as-deposited coatings had a nearly amorphous structure. Subsequent heating at a temperature above the PEEK melting point, 350 ºC, enabled homogeneous, semi-crystalline PEEK as a coatings matrix with spherulitic morphology to be produced (Fig. 1). TEM investigation revealed the presence of uniformly distributed γ-Al2O3 nanoparticles as well as agglomerates of both α-Al2O3 and γ-Al2O3 particles within the PEEK matrix. The coating thickness depended strongly on the time of EPD and equalled 45 μm, 80 μm and 120 μm after 20 s, 30 s and 60 s, respectively. Micro-scratch tests showed that all the coatings exhibited very good adhesion to the titanium alloy substrate, however, the thickest coating had the best adhesion. The composite Al2O3/PEEK coatings significantly improved the tribological properties of the Ti-13Nb-13Zr alloy, also in comparison with a polymer PEEK coated alloy. The Al2O3/PEEK coated alloy exhibited excellent wear resistance in comparison with uncoated ones and was better than the PEEK coated alloy. The coefficient of friction was reduced from 0.55 for an uncoated alloy to 0.30 and below 0.20 for the Al2O3/PEEK coated alloy in dry sliding and sliding in Ringer\u27s solution, respectively. The coatings increase the corrosion resistance of the alloy in Ringer’s solution at a temperature of 37 ºC. Please click Additional Files below to see the full abstract

EPD and Characterization of Graphite Oxide/Hydroxyapatite/Sodium Alginate Coatings Incorporated with Si3N4 or CuO Nanoparticles on Titanium Biomaterials

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Wpływ zawartości chromu w niskostopowych stalach konstrukcyjnych na ich właściwości elektrochemiczne i odporność korozyjną w roztworach wodnych rozprawa doktorska /

Tyt. z ekranu tytułowego.Praca doktorska. Akademia Górniczo-Hutnicza im. Stanisława Staszica (Kraków), 2012.Zawiera bibliogr.Dostępna także w wersji drukowanej.Tryb dostępu: Internet.Odporność na korozję stali nisko- i średniostopowych, właściwości elektrochemiczne żelaza w wodach termalnych, mechanizm i kinetyka korozji żelaza w roztworach wodnych zawierających CO2, H2S, anodowe roztwarzanie żelaza, wpływ anionów na przebieg reakcji anodowych, wpływ jonów chlorkowych, anionów węglanowych, tlenku węgla(IV), anionów siarczkowych, siarkowodoru, mechanizm wzrostu warstewek anodowych, wzrost magnetytu, warstewki syderytu, warstewki siarczkowej, mechanizm reakcji katodowych, reakcje katodowe w obecności rozpuszczonego dwutlenku węgla, reakcje katodowe w obecności rozpuszczonego siarkowodoru, wpływ mikrostruktury na mechanizm, kinetykę korozji stali węglowych, metodyka badań, materiały, stopy dwuskładnikowe Fe-Cr, odlewnicze, roztwory do badań, badania laboratoryjne, analiza fizykochemiczna wody termalnej ze stacji badawczej w Bańskiej Niżnej, Stargardzie Szczecińskim, badania elektrochemiczne, korozyjne, laboratoryjne, przemysłowe, techniki pomiarowe, chronowoltamperometria cykliczna, LSV, chronoamperometryczna polaryzacja przy stałym potencjale, elektrochemiczna spektroskopia impedancyjna, EIS, badania powierzchni, mikrostruktura stopów dwuskładnikowych Fe-Cr, badania elektrochemiczne żelaza w roztworach wodnych, 0.1M Na2SO4 nasycanym argonem, nasyconym CO2, w wodzie termalnej, mechanizm anodowego roztwarzania żelaza w roztworach wodnych, wpływ chromu na właściwości elektrochemiczne, korozyjne dwuskładnikowych stopów Fe-Cr, badania elektrochemiczne stopów Fe-Cr w 0.1M Na2SO4 nasycanym argonem, dwutlenkiem węgla, stopu Fe-5%Cr w wodzie termalnej pobranej w Geotermii Podhalańskiej S.A, w wodach termalnych w warunkach polowych, badania elektrochemiczne stopów Fe-Cr w Geotermii Podhalańskiej S.A. badania elektrochemiczne stopów Fe-Cr w Geotermii Stargard Szczeciński, wpływ chromu na właściwości elektrochemiczne i korozyjne dwuskładnikowych stopów Fe-Cr, badania powierzchni stopów Fe-Cr, struktura powierzchni stopów Fe-Cr, analiza składu chemicznego stopów Fe-Cr metodą AES, analiza składu chemicznego metodą XPS, badania powierzchni stopów Fe-Cr, badania elektrochemiczne komercyjnych stopów odlewniczyc

Determinants of organizational commitment in the creative sector on the example of cinema

Praca opiera się na identyfikacji uwarunkowań zaangażowania organizacyjnego w sektorze kreatywnym na przykładzie kina Cinema City Bonarka w Krakowie. Przybliża poznanie sektora kreatywnego, jego strukturę i znaczenie ekonomiczne oraz szczegółowo opisuje charakterystykę badanego kina.The work is based on the identification of the determinants of organizational involvement in the creative sector on the example of Cinema City Bonarka in Krakow. It introduces the knowledge of the creative sector, structure and economic importance. It also describes in detail the characteristics of the studied cinema

Microstructure, Micro-Mechanical and Tribocorrosion Behavior of Oxygen Hardened Ti–13Nb–13Zr Alloy

In the present work, an oxygen hardening of near-β phase Ti–13Nb–13Zr alloy in plasma glow discharge at 700–1000 °C was studied. The influence of the surface treatment on the alloy microstructure, tribological and micromechanical properties, and corrosion resistance is presented. A strong influence of the treatment on the hardened zone thickness, refinement of the α’ laths and grain size of the bulk alloy were found. The outer hardened zone contained mainly an oxygen-rich Ti α’ (O) solid solution. The microhardness and elastic modulus of the hardened zone decreased with increasing hardening temperature. The hardened zone thickness, size of the α’ laths, and grain size of the bulk alloy increased with increasing treatment temperature. The wear resistance of the alloy oxygen-hardened at 1000 °C was about two hundred times, and at 700 °C, even five hundred times greater than that of the base alloy. Oxygen hardening also slightly improved the corrosion resistance. Tribocorrosion tests revealed that the alloy hardened at 700 °C was wear-resistant in a corrosive environment, and when the friction process was completed, the passive film was quickly restored. The results show that glow discharge plasma oxidation is a simple and effective method to enhance the micromechanical and tribological performance of the Ti–13Nb–13Zr alloy

Effect of Cr Content on Corrosion Resistance of Low-Cr Alloy Steels Studied by Surface and Electrochemical Techniques

The electrochemical behavior of low alloyed Fe-Cr steels with 3 and 5% wt. of Cr in neutral Na2SO4 electrolyte combined with a detailed chemical and morphological characterization of these alloys performed by Auger electron spectroscopy, X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectrometry and scanning electron microscopy are presented here. The corrosion of low alloyed Fe-Cr steels proceeds in the prepassive range, with the formation of corrosion surface films having a duplex structure with outer iron oxide/hydroxide layer and inner Cr oxide-rich layer. The thickness, composition, and the morphology of the surface films vary as a function of chromium content in the alloy as well as conditions of electrochemical tests (temperature). Even a low chromium content shows a beneficial effect on the corrosion performances of the Fe-Cr steels. The chromium as a more active component than iron of ferrite increases the anodic activity of this phase, which results in a rapid saturation of the surface with the anodic reaction products forming a fine crystalline-like and compact layer of corrosion products. In this way, the chromium acts as a modifier of formation/crystallization of the iron-rich surface film (mainly magnetite) in the prepassive range

Effect of Cr Content on Corrosion Resistance of Low-Cr Alloy Steels Studied by Surface and Electrochemical Techniques

The electrochemical behavior of low alloyed Fe-Cr steels with 3 and 5% wt. of Cr in neutral Na2SO4 electrolyte combined with a detailed chemical and morphological characterization of these alloys performed by Auger electron spectroscopy, X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectrometry and scanning electron microscopy are presented here. The corrosion of low alloyed Fe-Cr steels proceeds in the prepassive range, with the formation of corrosion surface films having a duplex structure with outer iron oxide/hydroxide layer and inner Cr oxide-rich layer. The thickness, composition, and the morphology of the surface films vary as a function of chromium content in the alloy as well as conditions of electrochemical tests (temperature). Even a low chromium content shows a beneficial effect on the corrosion performances of the Fe-Cr steels. The chromium as a more active component than iron of ferrite increases the anodic activity of this phase, which results in a rapid saturation of the surface with the anodic reaction products forming a fine crystalline-like and compact layer of corrosion products. In this way, the chromium acts as a modifier of formation/crystallization of the iron-rich surface film (mainly magnetite) in the prepassive range

The Effect of Electrophoretic Deposition Parameters on the Microstructure and Adhesion of Zein Coatings to Titanium Substrates

Zein coatings were obtained by electrophoretic deposition (EPD) on commercially pure titanium substrates in an as-received state and after various chemical treatments. The properties of the zein solution, zeta potential and conductivity, at varying pH values were investigated. It was found that the zein content and the ratio of water to ethanol of the solution used for EPD, as well as the process voltage value and time, significantly influence the morphology of coatings. The deposits obtained from the solution containing 150 g/L and 200 g/L of zein and 10 vol % of water and 90 vol % of ethanol, about 4–5 μm thick, were dense and homogeneous. The effect of chemical treatment of the Ti substrate surface prior to EPD on coating adhesion to the substrate was determined. The coatings showed the highest adhesion to the as-received and anodized substrates due to the presence of a thick TiO2 layer on their surfaces and the presence of specific surface features. Coated titanium substrates showed slightly lower electrochemical corrosion resistance than the uncoated one in Ringer’s solution. The coatings showed a well-developed surface topography compared to the as-received substrate, and they demonstrated hydrophilic nature. The present results provide new insights for the further development of zein-based composite coatings for biomedical engineering applications

Microstructure and Selected Properties of Advanced Biomedical n-HA/ZnS/Sulfonated PEEK Coatings Fabricated on Zirconium Alloy by Duplex Treatment

In this work, sulfonated polyetheretherketone (S-PEEK)-based coatings, nanocrystalline ZnS and hydroxyapatite (n-HA) particles were developed on Zr-2.5Nb zirconium alloy substrates by electrophoretic deposition (EPD) combined with subsequent heat treatment. The properties of suspensions and deposition kinetics were studied. Cationic chitosan polyelectrolyte ensured the stabilization of the suspension and allowed for the co-deposition of all coating components on the cathode. The heating of the coated samples at a temperature of 450 °C and slow cooling resulted in sulfonation of the PEEK and the formation of dense coatings. The coatings were characterized by high roughness, hardness, modulus of elasticity and adhesion strength. The coatings revealed mild hydrophilicity, improved the electrochemical corrosion resistance of the alloy and induced the formation of hydroxyapatite with a cauliflower-like morphology on its surface during the Kokubo test. This work explored the great development potential of advanced sulfonated PEEK-based coatings, incorporating antibacterial and bioactive components by EPD combined with heat treatment to stimulate the surface properties of zirconium alloy for prospective dental and orthopedic applications. The antibacterial and osteoconductive properties of the obtained coatings should be further investigated